This invention relates to improvements in systems for manufacturing elongate sawblades such as saber sawblades. More particularly, the system provides extremely rapid automated manufacture of such blades and improved heat treatment thereof.
In the past, it has been the normal practice to manufacture elongate sawblades such as saber sawblades by punching blanks, having the general exterior configuration of such blades, from sheets of metal, arranging the blanks in a stack to cut teeth into them, deburring the blanks individually, setting (i.e. transversely offsetting) their teeth individually, and hardening them by heating them in an oven to the required "critical" temperature followed by rapid cooling or quenching. In each of the multiple operations described the blades must be handled individually, making the overall manufacturing process slow and expensive. Moreover, hardening of the blades by heating in an oven, followed by rapid cooling, results in hardening of the entire blade, including the shank portion, making the entire blade brittle and highly susceptible to breakage if subjected to excessive bending stress while in use.
In the past it has also been attempted to produce such blades from a continuous band of metal, retaining each blade as part of the integral band until all the manufacturing operations have been performed thereon, after which the blade is severed from the band. While such methodology is far superior to that described in the previous paragraph, the apparatus previously developed for performing such methodology has been extremely complicated, unreliable and difficult to maintain in synchronous operation due in large part to the use of electrical switches and solenoids for controlling pneumatic valves and cylinders. More important, such previous apparatus has not been nearly as rapid as is needed because of the slowness of the tooth-cutting operation wherein a rotary milling cutter is advanced toward the edge of the metal band in a direction parallel with the width dimension of the band. Since, in such an arrangement, the advancement of the cutter determines the depth of the tooth cut, the momentum of the cutter must be closely controlled to prevent too deep or too shallow a cut, at the expense of speed.